public class cuic {
    class Solution {
        public String modifyString(String ss) {
            char[] s = ss.toCharArray();
            int n = s.length;
            for(int i = 0;i<n;i++){
                if(s[i]=='?'){
                    for(char ch = 'a';ch<'z';ch++){
                        if((i==0 || ch != s[i-1]) && (i==n-1 || ch != s[i+1])){
                            s[i] = ch;
                            break;
                        }
                    }
                }
            }
            return String.valueOf(s);
        }
    }
}
